This invention relates to a multi-axis optical projector comprising an optical yoke for use, for example in a tool presetting or tool measuring system, for viewing of a specimen, such as a cutting tool, to measure tool profiles and to identify tool surface defects such as cracks, chips, wear patterns and coating abnormalities.
Optical comparators are often used in conjunction with tool presetting apparatus. Such prior art devices permit viewing of a specimen in silhouette (backlighting). When viewing a curved surface, a comparator can be expected to create a "fuzzy" image. This is because of parallax: the specimen usually is illuminated broadly on both sides of the focal point due to the usual low quality (normally plano-convex) lenses employed in a separate, discrete lamp house. The target is flood-lit both before and after the functional focal plane of the objective lens.
The traditional approach to determining edge position and tool size with presetting fixtures has been to make use of electromechanical touch probes or single view optical projectors. The latter method offers the advantage of non-contact dimensional determination for cutting tools such as those composed of polycrystalline diamond or other brittle materials. However, with current optical projectors, only a backlighted image is available for viewing a specimen. The prior art is devoid of optical arrangements employing a microscope or macro-capable telescope with dual, selectable objective lens systems providing for both backlighting and front lighting so that both tool measurement and surface integrity can be determined.
Moreover, current optical projectors used in conjunction with tool presetting applications inherently bias the presetting machine to either a right or left hand tool setting orientation.